As the consumption of energy increases, research has been conducted on solar batteries for converting solar energy into electric energy.
Particularly, Cu(In, Ga)Se2 (CIGS) solar batteries are widely used, which are pn hetero junction devices having a substrate structure including a glass substrate, a metal rear electrode layer, a p-type CIGS light absorption layer, a high resistance buffer layer, and an n-type window layer.
Some of light incident on such a CIGS solar battery is incident on a non-active area of the CIGS battery at which the photovoltaic effect does not occur.
If the size of a solar battery module increases, the portion of the non-active area of the module becomes considerable.
Therefore, research has been carried out to improve the light incident efficiency of solar batteries.